Nanotechnology is a rapidly evolving field of science involving creation at the nanoscale: the objects made measure between one and one hundred nanometres. For context, one nanometre is just one billionth of a metre, which is around one hundred thousand times smaller than the width of an average human hair. Nanotechnology was first envisioned by Professor Richard Feynman in his 1959 lecture, ‘There’s Plenty of Room at the Bottom’, but the term was coined in 1974 by Professor Norio Taniguchi, who used it to discuss the ability to design materials at the nanoscale.
There are some naturally occurring nanomaterials (e.g. in sand and volcanic ash) as well as nanostructures that can be found in many living organisms. For instance, there are some bacteria which can synthesise magnetic iron nano-minerals that help them to navigate using the Earth’s geomagnetic field. Scientists also have the ability to create nanostructures themselves by rearranging atoms within an object or binding atoms which have not been previously bound. Sometimes, unusual physical, chemical and biological properties will appear in materials at the nanoscale which are not ordinarily seen.
The Royal Society and Royal Academy of Engineering suggest that there are two main reasons why materials at the nanoscale often display different properties; the first of these is due to the larger surface area, which leads to the substance being more chemically reactive. Nanomaterials may also display quantum effects and the electronic, magnetic and optical behaviour of the material may then differ – this allows new, useful materials to be constructed. For example, materials may be manufactured so that they have a very high strength to weight ratios, high solubility or high conductivity, to suit their desired applications.
There are numerous nanomaterials with a plethora of varied properties, and so they are able to be used in practically all fields; nanosilver has antibacterial properties and is used in equipment like chopping boards, while carbon nanotubes can be added to the frames of tennis racquets to stiffen them and increase power when striking the ball. Zinc oxide particles provide great UVA protection and are used in sun creams, while titanium dioxide nanoparticles conduct electricity and are used to make anti-static clothing items. Although many of the aforementioned products may be considered mundane, these examples clearly illustrate the versatility of nanostructures, and the practical application of such in our everyday lives.
There are many other arguably more significant areas in which nanotechnology can have an impact; nanoparticles are often used in the medical field, as they have an important role in drug delivery. Nanoparticles can act either as the drug itself, or as the carrier. There are many challenges surrounding the use of large sized materials in medicine, such as poor solubility and poor absorption, but nanoparticles are able to move much more freely in the human body compared to these bigger materials and so are often much more useful.
Nanostructures can be used as delivery agents by encapsulating drugs which can then be delivered precisely to infected cells or tissues. Particles can be engineered so that they are attracted to diseased cells only, which reduces damage to healthy cells and has been shown to be much more effective than non-targeted delivery. The size of these nanoparticles also means that they have the potential to cross cell membranes like the blood-brain barrier. Other uses of nanotechnology in medicine include the use of nano-robots to make repairs to damaged cells, and the use of gold nanoparticles to sterilise surgical equipment.
Clearly, nanotechnology is very important and practical, both in everyday life and within medicine, but there is still so much opportunity for growth. Improvements in our understanding of nanotechnology may lead to many more sophisticated developments in multiple fields like medicine, cosmetics, clothing and home appliances in the future.
Despite the amazing things the application of nanotechnology has achieved, there are still lots of concerns and uncertainties surrounding the use of nanoparticles. There are many potential risks and researchers are concerned that some nanoparticles could be toxic. Many nanomaterials are possibly dangerous, but there is a great degree of uncertainty as some of these materials, which are not very harmful by themselves, could be toxic if inhaled in the form of nanoparticles. Many scientists worry that we may have an asbestos type issue on our hands. Asbestos was widely used in the late 19th and 20th centuries for its useful insulating and fireproofing properties, but is now known to be lethal. There are some physical similarities between asbestos fibres and carbon nanotubes, which has led to scepticism.
Recent tests carried out by the Medical Research Council Toxicology Unit in Leicester also showed the nanotubes having a carcinogenic effect on mice. While this is only evidence of the malfunction of one particular nanoparticle, many others could have similar issues which have simply not been discovered yet.
Although the size of nanoparticles is advantageous in certain aspects, their size is also seen as a drawback due to their ability to cross cell membranes. Nanoparticles can travel through the body to reach the blood and key organs like the brain, liver and heart, and although this is useful in drug delivery to normally inaccessible areas, the particles have been shown to cause issues such as lung inflammation and heart problems. In a study published in the Journal of Molecular Cell Biology, Chinese researchers discovered that a class of nanoparticles being widely developed in medicine (PA-MAMs) can cause lung damage by triggering a type of programmed cell death. Evidently there are certain dangers involved with nanotechnology – the question is whether these can be overcome.
Nanotechnology has the potential to revolutionise the way in which we live, as long as we can determine which nanomaterials are safe to use through the use of regulatory mechanisms and safety assessments. The National Cancer Institute in the US has said that it is likely that most nanomaterials will prove to be completely harmless, but in order to reach a point where we can safely and confidently expand the use of nanomaterials into the production of more consumer goods, we must carry out further research. Currently, there is insufficient knowledge and data pertaining to the detection of nanoparticles, their behaviour and their characteristics. In particular, the long-term effects of exposure to these nanoparticles must be investigated in much more depth.
The complexities behind nanotechnology are making development more difficult; however, its future does seem to be promising.
Image credit: Health Sciences and Nutrition, CSIRO via Wikimedia Commons